An intravenous (IV) catheter is an instrument that is used to introduce certain fluids such as saline solution directly into the bloodstream of a patient. Typically, a needle or other stylet is first introduced through the cannula portion of the catheter and into the skin of the patient at the desired location such as the back of the patient's hand or a vessel on the inside of the arm. Once insertion is complete, the needle is removed from the cannula portion of the catheter. After removing the needle, a fluid handling device such as a syringe is attached to the luer fitting located at the proximal end of the catheter hub. Fluid then flows directly from the fluid handling device through the catheter into the bloodstream of the patient.
When the needle is removed from the cannula, the health care worker must place the exposed needle tip at a nearby location while simultaneously addressing the task required to accomplish the needle removal. It is at this juncture that the exposed needle tip creates a danger of an accidental needle stick occurring which leaves the health care worker vulnerable to the transmission of various, dangerous blood-borne pathogens such as human immune virus (HIV) and hepatitis.
The risk of a contaminated needle stick is not just isolated to the health care worker inserting the intravenous catheter. Careless disposal of used needles can put other health care workers at risk as well. Even others outside the health care profession, for example those involved in the clean-up and final disposal of medical waste, are at risk of an accidental needle stick from a carelessly discarded needle.
The danger to health care workers and others outside the health care profession from accidental needle sticks has yielded the development of catheters with safety mechanisms in which the occurrence of such accidental needle sticks is prevented. An example of a catheter having a safety mechanism is disclosed in U.S. Pat. No. Re. 34,416 issued to Lemieux. A safety catheter is described which includes an element that covers the needle tip upon removal of the needle from the catheter. The safety element includes a split flange at its proximal end which is expanded by the needle as the needle is inserted into an undersized hole at the center of this flange. The safety element is thus held secure within the catheter hub by inserting the needle through the undersized hole which forces the outside perimeter of the split flange against the inside wall of the catheter hub. One of the drawbacks to this design is the amount of friction force exerted against the needle by the split flange. A tight fit of the flange against the catheter wall causes great friction against the needle making it difficult to be withdrawn from the catheter by the clinician. A lose fit leaves the flange prone to releasing prematurely from the catheter as the needle is withdrawn, creating the potential that the needle tip will be left exposed.
Another example of a catheter having a safety mechanism is disclosed in U.S. Pat. No. 6,117,108 issued to Woehr et al. A safety IV catheter is described including a resilient needle guard which protects the needle tip upon removal of the needle from the catheter hub. The needle guard includes an arm that includes an opening through which a needle passes causing axial movement of the arm. This axial movement forces the arm into a groove or behind a rib located on the inside of the catheter hub, capturing the needle guard in the catheter hub. A potential issue with this design develops when the needle guard is not properly seated into the. catheter hub. If the distal end of the needle guard arm is not in alignment with the groove in the catheter hub, excessive forces are placed on the needle causing a high drag force as the clinician removes the needle. And, since the needle guard arm is not properly seated in the groove, it may prematurely release from the catheter hub upon the removal of the needle leaving the needle tip exposed.
The prior art safety catheters all exhibit one or more drawbacks that have thus far limited their usefulness and full acceptance by health-care workers. What is needed therefore is a safety IV catheter that functions reliably, is easy and inexpensive to manufacture, and easy to use.